Large documents in persistant memory

Personne n'a encore pris cette issue.

After implementing #12 it was discovered that larger GUI documents could not be stored in the persistant flash memory. This is due to a known [limitation](https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-reference/storage/nvs_flash.html):

> String values are currently limited to 4000 bytes. This includes the null terminator. Blob values are limited to 508,000 bytes or 97.6% of the partition size - 4000 bytes, whichever is lower.

This means that larger GUI documents than 4000 bytes are not going to be able to be stored upon uploading remotely.
The workaround for this is to hard-code the large GUI when compiling a sketch, and passing it to mgui_init().

This limitation is not necessarily a big issue that needs to be solved, but it could be a good idea to implement a smart workaround for this so that the user gets a better experience using MicroGUI.

Commencez par examiner les limites de taille de la mémoire flash NVS d’ESP-IDF décrites dans l’issue ainsi que le cheminement de chargement des documents autour de mgui_init(). Déterminez comment les documents GUI téléversés à distance sont stockés et définissez l’achèvement de manière à permettre le stockage et l’utilisation à distance de documents de plus de 4000 octets sans dépendre de sketches codés en dur.

Rédigé par le modèle d'indexation à partir du texte de l'issue.